Potato plants are herbaceous perennials that grow about 60 cm high, depending on variety, the culms dying back after flowering. They bear white, pink, red, blue or purple flowers with yellow stamens resembling those of other Solanaceous species such as tomato and aubergine. The tubers of varieties with white flowers generally have white skins, while those of varieties with colored flowers tend to have pinkish skins. Potatoes are cross-pollinated mostly by insects, including bumblebees that carry pollen from other potato plants, but a substantial amount of self-fertilizing occurs as well. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties.

Based on historical records, local agriculturalists, and DNA analyses, the most widely cultivated variety worldwide, Solanum tuberosum ssp. tuberosum, is believed to be indigenous to the Chiloé Archipelago where it was cultivated as long as 10,000 years ago.

The potato was introduced to Europe in 1536, and subsequently by European mariners to territories and ports throughout the world. Thousands of varieties persist in the Andes, where over 100 varieties might be found in a single valley, and a dozen or more might be maintained by a single agricultural household. Once established in Europe, the potato soon became an important food staple and field crop. But lack of genetic diversity, due to the fact that very few varieties were initially introduced, left the crop vulnerable to disease. In 1845, a plant disease known as late blight, caused by the fungus-like oomycete Phytophthora infestans, spread rapidly through the poorer communities of western Ireland, resulting in the crop failures that led to the Great Irish Famine. The potato was the first vegetable inherited by the early Australians, the Aborigines. China now leads the largest potato crops seen throughout the world.

After potato plants flower, some varieties will produce small green fruits that resemble green cherry tomatoes, each containing up to 300 true seeds. Potato fruit contains large amounts of the toxic alkaloid solanine, and is therefore unsuitable for consumption.

Some commercial potato varieties do not produce seeds at all (they bear imperfect flowers) and are propagated only from tuber pieces. Confusingly, these tubers or tuber pieces are called "seed potatoes".

There are about five thousand potato varieties world wide. Three thousand of them are found in the Andes alone, mainly in Peru, Bolivia, Ecuador, Chile and Colombia. They belong to eight or nine species, depending on the taxonomic school. Apart from the five thousand cultivated varieties, there are about 200 wild species and subspecies, many of which can be cross-bred with cultivated varieties, which has been done repeatedly to transfer resistances to certain pests and diseases from the gene pool of wild species to the gene pool of cultivated potato species. Genetically modified varieties have met public resistance in the United States and in the European Union.

one wild potato species, Solanum fendleri, is found as far north as Texas and used in breeding for resistance to a nematode species attacking cultivated potatoes. Humans can subsist healthily on a diet of potatoes and milk.

A medium potato with the skin provides 27 mg of vitamin C, 620 mg of potassium, 0.2 mg vitamin B6 and trace amounts of thiamin, riboflavin, folate, niacin, magnesium, phosphorus, iron, and zinc. Moreover, the fiber content of a potato with skin (2 grams) equals that of many whole grain breads, pastas, and cereals. Potatoes also contain an assortment of phytochemicals, such as carotenoids and polyphenols.

Almost all the protein content of a potato is contained in a thin layer just under its skin.

Potatoes are also used to brew alcoholic beverages such as vodka and as food for domestic animals; potato starch is used to produce organic chemicals, in the textile industry, and in the manufacture of papers and boards.